Article 20

Analyzing Device History Reports

One of the most powerful, yet often overlooked PressureMAP reports is the one that lists all devices on a route or sector. This report is especially helpful when looking for big leaks—those that affect a lot of transducers. In fact, when analyzing the report, if you notice that only one device on the report changes frequently, it's likely that the transducer is defective. But when a major leak occurs, you'll typically see transducer reading changes at manifolds, end pipes and underground locations.

To show you an example, take a look at the report below. In looking at this History of All Devices on a Pipe/Sector Report (option # 2 on the PressureMAP Device History Menu), it appears that there's either a leak in the air pipe or maybe a cheater hose has been installed somewhere. First of all, notice that the source flow transducer (SF device #101) has been consistently posting readings of 80.0 and 81.0 SCFH—way too high for a transducer with an Optimum Air Usage (OAU) of only 16 SCFH. If you add up the current manifold flow transducer readings (device #s 105, 111, 116 and 121), the sum is only 32.7 SCFH, leaving over 47 SCFH unaccounted for.

Also, notice that the EP pressure transducer (device #122) is way below the commonly used endpipe pressure transducer standard of 7.5 PSI—another indicator of a leak or unrecorded air source in the pipe. With a delivery pressure this low, it is impossible to maintain the 6.0 PSI underground pressure transducer standard needed to fully protect the cables.

Then finally, since we're analyzing the report in its entirety, you might want to check the calculated OAUs. In this case, the combined OAU of all the manifolds is 10 SCFH, but the source OAU is 16 SCFH. It would be a good idea to recalculate these OAUs and make the necessary corrections in the PressureMAP data entry editor. You also might want to check for a manifold with an OAU of 6 SCFH that is not listed on the printout.

So there you have it, by analyzing the history report for all of the devices on a pipe, you can make some important discoveries. It's safe to say that PressureMAP initially alarmed on the high source flow and low endpipe devices, but apparently the condition causing the alarms was never corrected. If we were working this route, we'd install Flow Finders and purify the air pipe. There's no easier or more accurate way to verify total air pipe consumption and identify pipe leaks and cheater hoses.

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